1. Field of the Invention
This invention in general relates to photographic apparatus and in particular to improved cylindrical processing rollers for use in motor driven photographic processing apparatus of the type which spread a fluid processing composition in a thin, substantially uniform layer between selected layers of integral type, self-processable film units while advancing them to the exterior of a camera after they have been photoexposed.
2. Description of the Prior Art
Fully automatic photographic cameras which utilize integral type self-processable film units are well-known in the photographic field having been extensively described in the patent literature and in public use for several years now. These cameras, such as Polaroid Corporation's "SX-70" and "Pronto!" and Eastman Kodak Company's "EK-6" and "EK-8" cameras, are designed to automatically produce finished, waste-free color prints with virtually no operator involvement other than to compose the picture, perhaps focus, and then actuate the camera by depressing its cycle "start" button.
They accomplish this task through the use of specially designed interdependent function providing subsystems that are organized to carry out a programmed series of sequential operations which produce the finished print.
Once actuated, the order of camera operations begins with exposure of a film unit. Afterwards, the exposed film unit is advanced from its exposure location into engagement with a film processing subsystem or apparatus which initiates a diffusion transfer process in the film unit while transporting it to the exterior of the camera where it becomes accessible to the photographer. After the diffusion transfer process is initiated, it develops and forms a visible image in the film unit in a well-known manner.
The film units, as for example those described in considerable detail in U.S. Pat. Nos. 3,415,644; 3,594,165; and 3,761,268, normally contain all the photographic components necessary for the diffusion transfer process. Typically, the film units comprise, in general terms, a pair of superposed sheet elements, at least one being transparent, which serve to support layers of photochemical substances which may comprise photosensitive and image-receiving layers; and, as well, include a rupturable container of viscous processing fluid positioned adjacent a leading edge of the film unit and adapted to have its processing fluid released between the sheet elements to begin the diffusion transfer process. Release of the processing fluid is effected by the processing apparatus which operates to rupture the container and thereafter causes the released mass of processing fluid to flow between the sheet elements, opposite the direction of travel of the film unit, so that the processing fluid is progressively deposited between the sheet elements as a thin, uniform layer generally coextensive with the exposed area of the film unit. Upon completion of the diffusion transfer process, the final image is viewable through the film unit's transparent sheet element.
Photographic processing apparatus having the capability of performing the film advancing and fluid spreading operations outlined above are well-known in the art. Generally, such apparatus comprise a pair of rollers rotatably mounted in juxtaposed relation and resiliently urged toward one another to exert a pressure on the film unit as it is advanced between them in response to rotation of at least one of the rollers by a motor drive. The rollers typically are manufactured to precision tolerances so that the fluid layer thickness is properly sized for optimum photographic image quality and at least one of them is provided with a high-friction, sheet-contacting surface to provide a high traction force to transport the film unit to the outside of the camera without slippage and without visably damaging the surfaces of the film unit.
In addition to the precision tolerances and the high-friction, low-abrasion surface characteristic, these rollers generally are made of high strength alloys so that they either won't deform under the pressures generated during processing or deform only in a predictable manner, have high corrosion resistance, and are capable of retaining their original geometry after having processed a predetermined number of film units which is related to their expected useful life.
Another important feature these type of rollers have is their ability not to pick up particulate matter from the film units during processing. This feature is important since a substantial build up of particulate matter on the roller's surfaces would change their initial geometry and thereby compromise their fluid spreading and/or film transport performance.
One prior art device which satisfies the functional criteria for such film processing apparatus is described in considerable detail in U.S. Pat. No. 3,776,118 issued to John J. Driscoll et. al. on Dec. 4, 1973 and entitled "Photographic Film Processing Apparatus." Here the processing apparatus includes a roller assembly having first and second rotatably mounted juxtaposed elongated rollers which are resiliently urged toward one another. A pair of annular collars are provided on the first roller to define a minimum gap between the rollers to facilitate the initial introduction of the leading edge of a film unit between the rollers. The first roller is adapted to be selectively driven by a motor of the camera and, when so driven, its annular collars impart a rotary motion to the second roller. At least those portions of the two rollers adapted to contact one another are formed of a relatively low friction, impact resistant material, such as stainless steel, while at least the sheet-contacting facing surface of the first roller is formed of a relatively high friction material such as urethane. The urethane which is coated on the first roller operates to provide the relatively high traction force between the first roller and the film unit to transport the film unit outside of the camera and the stainless steel provides the strength necessary to withstand the pressures generated during the transport and fluid spreading phases. In addition to its strength, the stainless steel also possesses desirable corrosion resistant characteristics.
Although the performance of this type device is more than adequate as evidenced by its success in Polaroid Corporation's "SX-70" and "Pronto" cameras, it is, as one would expect from its design criteria, relatively expensive to manufacture. The urethane coating coupled with the precision tolerances in particular represent a major portion of its cost.
Another motor driven processing apparatus is that used in Eastman Kodak Company's "EK-6" and "EK-8" cameras. Here both rollers, which appear to be surface-hardened, steel, are motor driven and each has a roughened surface to provide the high traction force necessary for film transport. It appears that the roughened surfaces of these rollers may be achieved by conventional crush grinding techniques and may afterwards be plated for corrosion protection and wear resistance. The roughened surfaces of these rollers would also appear to be relatively expensive to manufacture.
A third example of a photographic processing roller suitable for use with integral self-processable film is described in U.S. patent application Ser. No. 901,910 filed on behalf of Harvey S. Friedman et. al. on May 1, 1978 and entitled "Photographic Processing Roller Having A Surface Roughened By Electric Discharge Machining." Here the roller's high-friction, low-abrasion surface is achieved by electric discharge machining a plurality of microscopic craters randomly spaced over a predetermined area of a roller's smoothly machined surface. The craters thus formed are sufficiently large to satisfy the high-friction requirement yet not so large that they mark the film during transport and processing.
The primary object of the present invention is to provide a photographic processing roller which satisfies the criteria outlined above by using a novel method which utilizes a pulsed laser to form a roughened surface which has a high-friction, low-abrasion characteristic.
Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the apparatus and method which are exemplified in the following detailed disclosure.